Probiotics fact sheet - by David Stache

What are probiotics?


Biotics fall into two main categories, prebiotics (fuel to stimulate bacterial growth) and probiotics (bacteria). The third category is synbiotics which contain both prebiotics and probiotics. As supplements, they are used to positively improve the bacteria that sit in the large intestine (colon). Probiotics are live bacteria and yeast found naturally in the body, and since around the mid 1990’s their health benefits have become increasingly popular.


The gastrointestinal tract is home to a huge amount of bacteria, some are the friendly type, some are the harmful type. A healthy gut will have a higher of ratio of friendly to harmful, helping to keep the gut working efficiently. There isn’t a lot of key evidence showing just how important gut health is to overall and optimal health, however issues such as IBS (Irritable Bowel Syndrome) have seen a large increase in recent years, with around 15 million people in the UK thought to be affected. 


The bacteria in the gut are all about balance, we need both good and bad in order to function fully, and help the gastrointestinal tract operate correctly. However, the balance can be skewed for many different reasons, most commonly by taking antibiotics, as this knocks out the balance of the bacteria. A bout of food poisoning will almost always affect your balance of gut bacteria, using probiotics following this is a good strategy to help improve overall gut health.


What do they do in my body?


Using a probiotic supplement helps balance the flora within the gut by increasing the numbers of helpful bacteria, in turn this inhibits the growth of harmful bacteria in the intestine. In addition to this, they also work to modify the gut immune response, and improve its barrier function, meaning the risk of certain infections can be reduced, specifically those within the gastrointestinal (GI) tract. An example of this is how they have been shown to improve the response to certain vaccines. More recently, it has been proven that probiotics are also capable of reducing the development of certain allergies, predominantly through modulating or adjusting the activity of the immune system.


What key health benefits do they provide?


As with all supplements, if you read the first page of Google, you will be led to believe that each one can cure everything. Probiotics are no different, with many claims of their benefits made with little evidence. However, there is strong evidence of the following health benefits of probiotics:


1.   Helping IBS - they have been shown to help reduce flatulence and stomach bloating in some people with IBS, and are a good starting point to helping with symptoms if you are diagnosed.


2.   Treating stomach bugs - they can help shorten an episode of diarrhoea caused by a stomach bug, there is also strong evidence that antibiotic associated diarrhoea symptoms can be prevented by using probiotics, this is because they protect against the antibiotics clearing out the protective gut bacteria.


3.   Lactose intolerance - a common digestive problem, probiotics have been shown to help reduce key symptoms such as diarrhoea, stomach cramps and flatulence.


4.   Boosting the immune system - recent evidence has shown promise in probiotics supporting the immune system, by helping to reduce the development of allergies. This is still an area where more key research is needed, but is looking promising.  


Are probiotics found in food, and if so, which foods can I eat to help my gut?


The use of foods containing probiotics has grown rapidly in the past few years, with imports from the Asian continent used for their health benefits as well as flavour. Probiotics are found naturally in many foods, such as:


·      kimchi (a Korean fermented cabbage)

·      miso (a Japanese soy based seasoning) 

·      kefir (a fermented dairy yoghurt product)

·      pickles

·      tofu

·      tempeh

·      dark chocolate

·      sauerkraut (a popular German dish made from pickled cabbage)

·      kombucha (a fermented tea) 


Why should I supplement with a probiotic? 


The importance of gut health is becoming more and more apparent, with many aspects of modern-day living shown to affect the gut flora, including contaminated foods, changes in the diet and stress. Digestive and immune health are becoming more important too, and whilst simply eating probiotic containing foods each day is beneficial, using a daily probiotic ensures that you’re constantly giving your gut the support it needs to do its job and help deliver optimal health. Probiotic supplements are also designed to protect the bacteria from stomach acid, which could stop bacteria from food reaching where it needs to get to.


How much should I take per day?


There is currently no set dosage recommendation for probiotics, however most brands range from 2 billion up to 10 billion culture forming units (CFU). This is generally the accepted dosage requirement for assisting with gut flora balance and improving health.


Are there any risks I should know about?


Upon first taking probiotics you can experience some gas or bloating, this is not common, but a sign you should lower the dose. Probiotics can also interact with some medication; therefore, you should let your doctor know you are taking them if they are looking to prescribe you with medication. People who have artificial heart valves have an increased risk of bacterial infections whilst taking probiotics. 



Didari T, Solki S, Mozaffari S, et al. A systematic review of the safety of probioticsExpert Opinion on Drug Safety. 2014;13(2):227–239.



Hempel S, Newberry SJ, Maher AR, et al. Probiotics for the prevention and treatment of antibiotic-associated diarrhea: a systematic review and meta-analysisJAMA. 2012;307(18):1959–1969.



Moayyedi P, Ford AC, Talley NJ, et al. The efficacy of probiotics in the treatment of irritable bowel syndrome: a systematic reviewGut. 2010;59(3):325–332.